Efficacy of ethanolic leaf extracts of Carica papaya and Terminalia catappa as molluscicides against the snail intermediate hosts of schistosomiasis

The study evaluated the molluscicidal effects of ethanolic leaf extracts of two Nigerian indigenous medicinal plants; Terminalia catappa and Carica papaya. Different concentrations 2500, 630, 160, 40 and 10 ppm were prepared from the stock solution of the extracts. Adult Biomphalaria pfeifferi and Bulinus globosus were exposed to these different graded concentrations. Mortalities were observed at intervals of time. There were strong positive correlations between mortalities observed in snails and extracts' concentrations; R2 = 0.997 and 0.952 in T. catappa exposed B. pfeifferi and B. globosus respectively and R2 = 0.925 and 0.937 in C. papaya exposed B. pfeifferi and B. globosus respectively. The lethal concentration (LC50) values for B. pfeifferi and B. globosus were (864.1, 1095.7 ppm) and (2716.3, 619.1 ppm) for T. catappa and C. papaya ethanol extracts respectively. The corresponding LC90 values were (1222.8, 1874.9 ppm) and (4515.9, 1180.7 ppm) for T. catappa and C. papaya ethanol extracts respectively. The results from the lethal concentration values showed that B. pfeifferi is more susceptible to T. catappa while B. globosus is more susceptible to C. papaya ethanolic leaf extracts.